Astrochemical Inheritance of Terrestrial Planets Water from Local Wet Silicates

Abstract

The delivery of water to the inner Solar System rocky planets, including Earth, remains debated, as standard models assume that they formed from dry grains, inside the snowline of the protosolar nebula. However, a recent work showed that a not-negligible amount of water formed during the prestellar phase could have been retained by pebbles and planetesimals at the Earth's orbit in enough quantities to reproduce its water content. This study was based based on quantum mechanics (QM) calculations of the binding energy (BE) of water on amorphous ice and on a kinetic approach. Here, we present new QM calculations of the BE of water frozen on the surface of silicate grains, and show that it is on average about twice larger than that on the amorphous ice. The contribution of this first layer of frozen water increases the dust temperature at which frozen water can be retained. This provides a local source of water not only for the Earth, but also for the inner rocky planets. The predictions from our model are in agreement with the available estimates of water content in terrestrial planets. This suggests that water delivery from the outer Solar System may not be required.

accepted for publication in MNRAS

References in corpus (8)

• On the Location of the Snow Line in a Protoplanetary Disk
• Evolution of Water Reservoirs on Mars: Constraints from Hydrogen Isotopes in Martian Meteorites
• H2 formation on interstellar grains and the fate of reaction energy
• Origin of Water in the Terrestrial Planets: Insights from Meteorite Data and Planet Formation Models
• Disk evolution and the fate of water
• Was Earth's water acquired locally during the earliest phases of the Solar System formation?
• The role of the pre-exponential factor on temperature programmed desorption spectra: A computational study of frozen species on interstellar icy grain mantles
• Homogeneous accretion of the Earth in the inner Solar System